1. Field of the Invention
Systems consistent with the disclosure provided herein relate to a touch sensor system, and more particularly, to a touch sensor system which receives vibration wave or elastic wave and determines a touch point accurately using the vibration received at the touch point.
2. Description of the Related Art
Display technologies, which were mostly focused on TVs or computer monitors, have recently been applied to the fields of mobile devices such as phones, PMPs, MP3, GPS for use in vehicles, and are expected to be further extended to the virtual displays. While conventional displays provide limited function of conveying visual information, there has been consistent demand for more convenient interface, and the displays have now been developed to provide function of keyboard or mouse, i.e., the function of window through which information can be inputted. Such display with multi-function is collectively called touch screen or touch panel.
While there are various technologies that have been introduced to implement touch screen, these technologies may be divided mainly into three schemes depending on manners of estimating a location at which an external touch is made.
First, the electric resistive touch panel is most widely used. The electric resistive touch panel is fabricated by forming longitudinal and transversal arrangement of transparent electrodes on the surface of the display window and coating a top thereof with insulating layer.
A conductance is connected at a point where the touch is made, and it is possible to discriminate the touch point from the transparent electrodes in longitudinal and transversal arrangement. Although the fabrication thereof is complicated, due to use of advanced semiconductor processing, relatively improved techniques and much simpler algorithms have enabled use of this technology to increase.
However, use of additional layers including the transparent electrodes which are mounted on the glass substrate compromises brightness. Accordingly, more power is necessary to output uncompromised brightness. However, this requirement is almost fatal to mobile display which consumes power from the low-capacity mobile power source. Further, since the fabrication technique is based on the semiconductor processing which deals with the entire substrate, it is practically not efficient for the manufacture of wide touch panels.
Second, touch panel by capacitance measurement may be used. This scheme places capacitance sensors on upper, lower, left and right outer sides on the touch panel and discriminates a location of touch when an object with predetermined potential such as a finger is placed on the touch panel, based on a difference of potentials charging the respective capacitance sensors. The capacitive touch panel provides good sensitivity and is particularly sensitive to finger movements.
However, the scheme is basically not applicable to the transparent substrate such as glass, so requires separate touch panel such as notebook pad, which can be a great obstacle to integration.
Lastly, a touch panel driven by elastic wave sensing may be used. Elastic wave transmitters/receivers may be arranged periodically on upper or lower portion of the touch panel, mostly represented by glass, and an elastic wave path is made on the touch panel surface using the elastic wave reflector. Accordingly, when an object absorbing elastic wave such as finger touches on the touch panel surface, offset of elastic wave at the touch point is detected and the exact location is determined based on the detection. This technique has gained much attention, particularly because the elastic wave transmitters/receivers, which do not contribute to the display, are placed on the outer side of the touch panel to thus enhance brightness of the light source.
However, the technique consumes much power to consistently output elastic wave even when there is no touch inputted. The requirement for arranging reflector of transmitters/receivers also causes the construction to be complicate.
As explained above, since various forms of conventional touch panels need to consume much power, it is difficult to apply the conventional touch panels to ultra-small mobile devices. Further, since the conventional technologies require complicated structure, these are particularly not easily applicable to the future wide displays. Accordingly, a new concept of touch panel is required, which has simpler structure and consumes less power.